Yeah, I just checked to see if this forum supports "spoiler tags", and it doesn't seem to. However, setting the font color to white accomplishes something simlar. If you highlight the rest of this sentence, which is written in white, you can read it (or at least I can in my browser).
Be warned, though, that if you use the "Quote" button when replying to such post, you will see the hidden content in all its glory, just surrounded with the color tags.
And since this forum displays quoted texts in grey background, the hidden content becomes visible to everyone else too when quoted. Just noticed this when I tried to preview this reply.
I too suggest a dedicated thread or even a subforum.